RADC-TR-85-229, FINAL TECHNICAL REPORT: RELIABILITY PREDICTION FOR SPACECRAFT (DEC-1985) [AD-A164747]

RADC-TR-85-229, FINAL TECHNICAL REPORT: RELIABILITY PREDICTION FOR SPACECRAFT (DEC-1985) [AD-A164747]., This study provides the basis for improving the utility of Mil-HDBK-2l7 for reliability prediction of spacecraft components and systems. The reliability performance histories of 300 satellite vehicles, which were launched between the early 1960's through Jan 84, were reviewed and analyzed during the course of the study. Analysis of over 2500 reports of malfunctions indicated strong evidence of a decreasing failure rate with time in orbit. The cause for the decreasing hazard was found to be traceable primarily to design and environmental causes. In general, however, it was found that current predictions over-estimate the failure rate by at least a factor of two and that the excess of predicted over observed failures increases with time in orbit. Three methods are provided for spacecraft reliability prediction. In order to account for the decreasing hazard, two of the procedures use a Weibull model with parameters based upon similar spacecraft mission types. A third method uses modifications of Mil-Hdbk-2l7 procedures to account for the overestimation of failure rates which result when procedures are used.